Postreplication Roles of the Brucella VirB Type IV Secretion System Uncovered via Conditional Expression of the VirB11 ATPase.

摘要: ABSTRACT Brucella abortus, the bacterial agent of worldwide zoonosis brucellosis, primarily infects host phagocytes, where it undergoes an intracellular cycle within a dedicated membrane-bound vacuole, Brucella-containing vacuole (BCV). Initially endosomal origin (eBCV), BCVs are remodeled into replication-permissive organelles (rBCV) derived from endoplasmic reticulum, process that requires modulation secretory functions via delivery effector proteins by VirB type IV secretion system (T4SS). Following replication, rBCVs converted autophagic vacuoles (aBCVs) facilitate egress and subsequent infections, arguing bacterium sequentially manipulates multiple cellular pathways to complete its cycle. The T4SS is essential for rBCV biogenesis, as VirB-deficient mutants stalled in eBCVs cannot mediate biogenesis. This has precluded analysis whether apparatus also drives stages To address this issue, we have generated B. abortus strain which function conditionally controlled anhydrotetracycline (ATc)-dependent complementation deletion virB11 gene encoding VirB11 ATPase. We show murine bone marrow-derived macrophages (BMMs) early production optimal biogenesis replication. Transient expression prior infection was sufficient normal replication but led inactivation decreased aBCV formation release, indicating these postreplication dependent. Hence, our findings support hypothesis additional, roles IMPORTANCE Many pathogens encode specialized systems deliver cells their cycles. Because events occur sequentially, classical genetic approaches late apparatuses play, secretion-deficient proceed past initial defect. Here designed functionally controllable (T4SS) pathogen decipher temporal requirements during bacterium’s macrophages. By controlling ATPase, energizes T4SS, not only required generate replicative organelle contributes completion egress. Our expand upon pathogenic illustrate targeting ATPases useful strategy manipulate activity systems.